A series of immunoconjugates have been prepared consisting of several types of toxins and drugs conjugated to anti-melanoma antibody 9.2.27, and the D3 antibody to L10 hepatocellular carcinoma. 9.2.27 formed potent ID50=10 to the -4 to 10 to the -13M) immunoconjugates with intact abrin and ricin, gelonin, pokeweed antiviral protein (PAP) and the A chains of ricin and abrin. These are the most potent conjugates yet reported in the literature. Immunotoxins of 9.2.27 were highly selective, killing antigen positive cells at concentrations between 1000 to 50,000 times less than antigen negative cells. D3 conjugates of gelonin, PAP, ricin and abrin A chains varied in potentency from 10-9 to 10-11. D3 conjugates with whole abrin, however, were reproduciably more toxic at 10 to the -12 to 10 to the -13 (ID50) and still retained a selectively of 100 to 1000 fold. Within the last 4 months of the fiscal year, Dr. Alarif has undertaken the conjugation of the chemotherapeutic drugs emthotrexate adriamycin, and bleomycin. A general ligand system has been developed using a poly-lysine-drug linker conjugated by disulfide linkage to antibody. Bleomycin conjugates have been found to be the most potent 3 x 10 to the -8 M ID50), similar to levels of toxicity of free drug. Our evaluation of toxin conjugates in animals against established palpable tumors had indicated we would almost completely inhibit tumor growth.